During the retreat of the northern seasonal polar ice cap
the very different optical and thermal characteristics of
ice-free regolith, CO2 and H2O ice coverages
together with their seasonally changing horizontal
configurations drive an interesting set of terrain-induced
mesoscale circulations. In simulations using flat topography
these circulations manifest themselves as separate or merged
daytime circulation cells above the edges of different ice
coverage regions. Slope winds driven by the the regional
topography are also probably ubiquituous.

The mesoscale circulation patterns may play a role in the
polar water transport phenomena; the circulation cell can
plausibly return water sublimed from exposed H2O ice to
above the CO2 or H2O ice for recondensation and
deposition. The albedo of the interior of the polar cap has
been observed to brighten and the brightening may be caused
by the accumulation of fresh H2O ice as described
above.

We have used the Department of Meteorology 2-D Mars
Mesoscale Circulation Model --- a x-\sigma coordinate
system primitive equation model --- to simulate some of the
plausible northern polar cap edge region spring-summer
(Ls= 50\circ\ldots120\circ) mesoscale
circulations and the associated water transport
characteristics.

The author(s) of this abstract have provided an email address
for comments about the abstract:
Tero.Siili@fmi.fi